Power switch with magnetic blow-out chamber and an adjacent arc chamber having spring-mounted walls within which the switch contacts are located



y 25, 1965 P. BALTENSPERGER 3,185,801

POWER SWITCH WITH MAGNETIC BLOW-OUT CHAMBER AND AN ADJACENT ARC CHAMBER HAVING SPRING-MOUNTED WALLS WITHIN WHICH THE SWITCH CONTACTS ARE LOCATED Filed Oct. 15, 1962 INVENTOR PoduL Boltensperger ATTORNEYS United States Patent Ofihce 3,185,801 Patented May 25, 1965 3,185,801 PQWER SWITCH WITH MAGNETIC BLOW-OUT CHAMBER AND AN ADEACENT ARC CHAMBER HAVING SPRING-MOUNTED WALLS WlTli-HN WHICH THE SWITCH CUNTACTS ARE LOCATED Paul Baltensperger, Wurenios, Aargau, Switzerland, as-

signor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Filed Oct. 15, 1962, Ser. No. 230,615 Claims priority, application Switzerland, Jan. 29, 1960,

2 Claims. (Cl. 20014-7) This application, which is a continuation-in-part of my co-pending application Serial No. 83,791, filed January 19, 1961, now abandoned, relates to are extinction chambers for heavy duty electrical switches of various types and more particularly to an improved construction for the extinction chamber which adapts itself automatically to various intensities of the current being disconnected by the switch contacts.

In heavy duty switches, particularly those provided with an open extinction chamber in which the are drawn between the contacts is to be extinguished, it has been established that a narrow chamber is more advantageous for extinguishing arcs produced upon disconnection of low load currents and that a wide chamber is similarly more advantageous for extinguishing arcs attributable to high load currents. In switches provided with a magnetic type of arc blow-out, the arc is blown by the magnetic field into the extinction chamber wherein it is cooled and simultaneously lengthened between its roots until it finally breaks. Cooling of the arc is a material factor in disrupting the arc and it has been established that the cooling eifect is greatest when the arc burns as close as possible to the walls of the extinction chamber. So far as is presently known, the extinction chambers of these switches are so dimensioned was to establish a positive disconnection for the highest current rating of the switch. The unavoidable consequence of this is that the chamber is or" poor design for handling currents lower than the maximum rating because these lower currents will be less cooled in the chamber due to the fact that the arc burns too far away from the cooling wall parts of the chamber.

In order to improve the disconnecting ability of the switch for low currents, additional expedients have heretofore been used. For example, additional blowing of the arc with compressed air has been provided. It has also been found that in switches provided with closed are extinction chambers, such as air blast or low oil content switches, the conditions for disconnecting with high and low currents are diiierent, and that an adaptation of the switch to these diiferent conditions is desirable. For this reason, it has been proposed to vary the opening of the blow-out valve controlling the discharge of compressed air into the extinction chambers of air blast switches in a manner dependent upon the magnitude of the current to be disconnected thus to obtain a blast intensity which varies in the same sense as the current.

All of the known expedients which have been explained above have the disadvantage in that they are quite expensive. For switches provided with a magnetic type of blow-out, any additional blowing action with compressed air necessitates a compressed air generator. For switches of the air blast type in which a source of compressed air is provided, a modification of the valve controlling the discharge of compressed air from the source into the switch so as to regulate the valve opening in accordance with the magnitude of the current to be disconnected requires special windings on the valve control. All of such measures obviously entail a great increase in the cost of the switch.

In accordance with the present invention, one attains a substantial simplification in adapting the extinction chamber to the various current intensities which the switch is designed to handle, and the improvement is characterized in that the volume of the extinction chamber in which the switch contacts are located is adjusted automatically in dependence upon the magnitude of the switching current. In particular, the extinction chamber is constructed with at least one elastic wall which is movable toward or away from an opposite wall of the chamber. For low currents, the chamber walls will be closer together and for high currents, the chamber walls will be farther apart. Thus the arc will burn close to the chamber walls for low currents and hence optimum cooling of the arc will be obtained for all switching currents. In accordance with the invention, the distance between the walls is controlled by the load current being disconnected. One wall of the extinction chamber may be stationary and the other movable, or both walls of the chamber may be constructed to move towards and away from each other. Moreover, at least one wall of the extinction chamber may be pivoted at one end and spring mounted at the other, or the movable wall may be mounted on springs at both ends. The movable wall or walls may be displaced, for example, by the pressure produced by the are as it burns, this pressure being higher for high arc currents than it is for low arc currents.

The inventive concept will be described with respect to two different embodiments thereof and these embodiments are illustrated in the accompanying drawings.

FIGURE 1 of the drawings is a side view in vertical section of an electric switch provided with an extinction chamber in which the switch contacts are located and wherein means are provided for magnetically blowing the are formed between the switch contacts as they separate upwardly between the walls of the chamber, the opposite walls of this chamber being pivotally mounted at their upper ends and supported elastically by springs at their lower ends so that the walls move pivotally apart with a force which varies with the magnitude of the current flowing between the switch contacts upon separation.

FIGURE 2 is a vertical transverse section taken on line 22 of FIG. 1; and

FIGURE 3 is also a vertical transverse section similar to FIG. 2 but showing a modified construct-ion wherein the opposite walls of the extinction chamber are mounted on springs at the lower end as well as at the upper end so that the walls move parallel to themselves rather than pivotally as in the construction shown in FIGS. 1 and 2.

With reference now to the drawings and to FIGS. 1 and 2 in particular, the electric switch includes a casing 1 having in the lower part thereof a drive mechanism, not illustrated, which actuates an insulated rod 2 that is articulated to the movable contact arm 3 which is pivotally mounted on the lower contact piece 4 which projects outwardly through the back wall of the casing 1. The stationary contact member 5 of the switch, which engages and is disengaged from the contact at the upper end of movable contact arm 3, is secured to another contact piece 6 located above contact piece 4 and which likewise projects outwardly through the back wall of casing 1.

Located above the switch contacts 3, 5 are a pair of spaced apart arcing horns '7 and 8. Horn 7 is connected electrically through the winding 9 of the electromagnetic blow-out device 10 to the contact piece 6 and arcing born 8 is electrically connected by means of a rigid conductive rod 11 to the other contact piece 4. These horns 7, 8 project vertically upward between the walls of the magnetic blow-out chamber 12 in which are located a plurality of vertically extending, parallel spaced, metallic walls 13 which sub-divide the blow-out chamber 12 into a plurality of sub-chambers into each of which the arc is blown and stretched until it is ultimately broken and extinguished.

Located below and communicating with the magnetic blow-out chamber 12 is another are chamber part which is established by spaced walls 14, 15 between which the switch contacts 3 and 5 are located. Walls 14, are not fixed in position but rather are, in accordance with the invention, arranged elastically for movement apart from an initial position in accordance with the pressure forces created upon separation of the switch contacts 3, 5. To this end, the upper ends of walls 14, 15 are pivotally mounted at points 15, 17, adjacent the entrance to blowout chamber 12 while the lower ends of these walls are supported against springs 18, 19 respectively.

In addition to the blow-out coil 9, the electromagnetic blow-out device includes a magnetic structure having horizontal parallel spaced legs 20, between which the chamber 12 is located. The magnetic fiux established upon energization of coil 9 as the contacts 3, 5 disengage passes between the legs 20, 20 and hence transversely through the chamber 12.

Assuming that the switch contacts 3, 5 are closed and that the switch is caused to be tripped to an open position, lever 2 will be shifted to pull switch contact arm 3 away from the stationary contact member 5. This will cause an are 21 to be initially established between the contacts and simultaneously magnetic blow-out coil 9 will be energized. Due to the loop effect and the thermal uplift, the arc will then be caused to travel upwards between the walls 14, 15 and be transferred to the lower ends of the arcing horns '7, 8. The walls 14, 15 will separate, compressing springs 18, 19, by an amount dependent upon the physical forces involved in the are which are determined by the magnitude of the current passing through contacts 3, 5 when they separate. As the are 21 continues to rise, it comes into the influence of the magnetic field established transversely of the chamber 12 and thus receives a further impetus for driving it upward into the sub-divisions of the arc chamber 12 established by the partitions 13. The are is stretched upwardly in loop form into each of these sub-divisions and is thus finally ruptured and extinguished.

Due to the elastic mounting of the chamber walls 14, 15 the distance between them will be determined by the pressure produced by the arc in the chamber. When this pressure is high, which is indicative of a high switching current, the walls 14, 15 will be forced apart, rotating them in opposite directions around their respective pivots 16, 17 and compressing the springs 4. When the arc pressure is low, which is indicative of a low switching current, there is a correspondingly less force tending to force the walls apart. Thus they remain closer together and hence the are attributable to the low switching current will burn close to the chamber walls with optimum cooling.

In this embodiment of the invention, both walls 14, 15 of the extinction chamber have an elastic characteristic to effect a change in the volume of the chamber proportional to the magnitude of the switching current. However, it is evident that a similar result can be obtained by making one of the walls elastic and the other stationary.

In the embodiment shown in FIG. 3, both walls 14, 15 of the extinction chamber are also arranged for movement towards and away from each other dependent upon the magnitude of the switching current as measured by the pressure created by the arc but each wall is mounted entirely by springs. Thus in addition to the compression springs 18, 19 at one end of each wall as in FIGS. 1 and 2, other compression springs 22, 23 are used in lieu of the pivot mountings 16, 17. The operation of the FIG. 3 embodiment is essentially the same as that of FIGS. 1 and 2 except that the walls 14, 15 remain subs antially parallel as they move towards and away from each other.

The arrangement according to the invention has the advantage that it permits, with simple mechanical means, an adaptation of the extinction chamber to various current intensities and thus enables the heavy duty switch, particularly one with a magnetic blowout for the arc to be equally efiective for both high and low values of the load current to be disconnected by the switch.

In conclusion it will be understood that while various embodiments have been described and illustrated, other modifications as regards structure and arrangement of parts may be made without, however, departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In an electrical switch, the combination comprising a stationary switch contact and a movable switch contact arranged to engage and be disengaged from each other, a magnetic blow-out chamber located above said switch contacts, a pair of spaced arcing horns extending upw. jdly into said blow-out chamber, means electrically conne .ing one of said arcing horns with one of said switch contacts, means electrically connecting the other arcing horn with the other switch contact through a magnetic blow-out coil, and a further are chamber portion in communication with said blow-out chamber, said further arc chamber portion including a pair of spaced walls within which said switch contacts are located, means pivotally mounting said walls at one end thereof adjacent the entrance to said blow-out chamber and spring means engaged with said walls at a distance remote from said pivotal mounting means thereby enabling said walls to be pivotally moved apart against a counter biasing action of said spring means, the extent of said wall movement being variable with the magnitude of the current passing through said contacts when they disengage.

2. In an electrical switch, the combination comprising a stationary switch contact and a movable switch contact arranged to engage and be disengaged from each other, a magnetic blow-out chamber located above said switch contacts, a pair of spaced arcing horns extending upwardly into said blow-out chamber, means electrically connecting one of said arcing horns with one of said switch contacts, means electrically connecting the other arcing horn with the other switch contact through a magnetic blow-out coil, and a further arc chamber portion in communication with said blow-out chamber, said further arc chamber including a pair of parallel spaced walls within which said switch contacts are located, and an elastic mounting for said parallel spaced walls including spring means engaging said walls at spaced apart locations thereon thereby enabling said walls to be moved apart against a counter biasing action of said spring means while remaining essentially parallel to each other, the extent of said wall movement being variable with the magnitude of the current passing through said contacts when they disengage.

References Cited by the Examiner UNITED STATES PATENTS 2,345,724 4/44 Baker et al 200-148 2,998,499 8/61 Mankotf et al 200150 FOREIGN PATENTS 1,203,659 8/59 France.

BERNARD A. GILHEANY, Primary Examiner.

RCBERT K. SCHAEFER, Examiner. 

1. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A STATIONARY SWITCH CONTACT AND A MOVABLE SWITCH CONTACT ARRANGED TO ENGAGE AND BE DISENGAGED FROM EACH OTHER, A MAGNETIC BLOW-OUT CHAMBER LOCATED ABOVE SAID SWITCH CONTACTS, A PAIR OF SPACED ARCING HORNS EXTENDING UPWARDLY INTO SAID BLOW-OUT CHAMBER, MEANS ELECTRICALLY CONNECTING ONE OF SAID ARCING HORNS WITH ONE OF SAID SWITCH CONTACTS, MEANS ELECTRICALLY CONNECTING THE OTHER ARCING HORN WITH THE OTHER SWITCH CONTACT THROUGH A MAGNETIC BLOW-OUT COIL, AND A FURTHER ARC CHAMBER PORTION IN COMMUNICATION WITH SAID BLOW-OUT CHAMBER, SAID FURTHER ARC CHAMBER PORTION INCLUDING A PAIR OF SPACED WALLS WITHIN WHICH SAID SWITCH CONTACTS ARE LOCATED, MEANS PIVOTALLY MOUNTING SAID WALLS AT ONE END THEREOF ADJACENT THE ENTRANCE TO SAID BLOWOUT CHAMBER AND SPRING MEANS ENGAGED WITH SAID WALLS AT A DISTANCE REMOTE FROM SAID PIVOTAL MOUNTING MEANS THEREBY ENABLING SAID WALLS TO BE PIVOTALLY MOVED APART AGAINST A COUNTER BIASING ACTION OF SAID SPRING MEANS, THE EXTENT OF SAID WALL MOVEMENT BEING VARIABLE WITH THE MAGNITUDE OF THE CUTTENT PASSING THROUGH SAID CONTACTS WHEN THEY DISENGAGE. 